This study is designed to reexamine a well characterized cohort of 2,366 diabetic persons in Southern Wisconsin in order to determine progression and new development of diabetic retinopathy and visual impairment. Participants will be examined in their home communities in a mobile examining van. As part of the evaluation, refraction, visual acuity, intraocular and blood pressure measurments according to standardized protocols, and determination of urine protein, blood glycosylated hemoglobin, and plasma C-peptide levels will be performed. Objective recording of retinopathy by use of stereoscopic fundus photography combined with a standardized protocol for grading the retinopathy will be used. Grading of the stereo photographs will provide a sensitive and reproducible method for detection of the appearance or progression of retinopathy. The incidence and causes of visual impairment will be determined. The incidence of retinopathy and of its various component lesions will be evaluated with respect to risk factors, such as duration and age at diagnosis of diabetes, glycosylated hemoglobin level, blood pressure level and smoking history as ascertained four years previously. The vital status of patients will be determined to provide data regarding the relationship between severity of retinopathy and other characteristics with prognosis for life.